Synchronizing attachment for clocks.



B. F. MERRITT. SYNGHRONIZING ATTAGHMENT FOR CLOCKS APPLICATION FILEDMAR. 9, 1908.

Patented May 17, 1910.

WLWmq-c I UNITED STATES PATENT OFFICE.

BENJAMIN F. MERRITT, OF CANTON, MASSACHUSETTS, ASSIGNOR TO DEY TIMEREGISTER COMPANY, OF SYRACUSE, NEW YORK, A CORPORATION OF NEW YORK.

SYNCHRONIZING ATTACHMENT FOR CLOCKS.

To all whom it may concern:

Be it known that I, BENJAMIN F. MER- RITT, a citizen of the UnitedStates, residing at Canton, in the county of Norfolk, Massachusetts,have invented certain new and useful Improvements in SynchronizingAttachments for Clocks, of which the following is a specification,reference being had to the drawing accompanying and forming part of thesame.

Where several clocks are employed in an establishment it is of coursedesirable that all the clocks show the same time. This is especiallydesirable, in fact it is practically imperative, where several timerecorders are used for recording the time of arrival and departure ofemployees. It is, however, difficult to keep two or more clocks going atprecisely the same rate for any length of time except at the expense ofconsiderable time and trouble in inspecting and regulating the clocks atfrequent intervals.

I have therefore been led to devise my present invention, which has forits chief object to provide means whereby a clock can be controlledelectrically from a master clock and therefore be made to keep time withcomplete accuracy with respect to such master clock.

A further object is to provide means, for the purpose stated, whichshall be simple and cheap in construction without sacrificce of accuracyor reliability of operation.

In carrying out my invention in the preferred manner I dispense with theusual pendulum and scape wheel in the controlled or subsidiary clock orclocks, and substitute a scape wheel having preferably a single tooth,omitting the pendulum altogether. This scape wheel, which may beconveniently termed a scape arm is connected with the escapement arborof the clock, so that the release of the arm at regular intervals willproduce the desired regularity in the motion of the clock-train.

In applying the invention to timerecorders I prefer to have the pinionon the escapement arbor, and the gears connecting the same with theminute arbor, so proportioned that a complete revolution of the scapearm will permit the minute arbor or spindle to advance a spaceequivalent to one minute of time, (for the reason that workmenstime-recorders do not, as a rule, take account of intervals of less thana Specification of Letters Patent.

Application filed March 9, 1908.

Patented May 1'7, 1910.

Serial No. 419,885.

minute), and also to construct the anchor so that it will at eachvibration permit such complete revolution of the scape arm. The anchoritself is provided with an armature, preferably located near the anchorshaft, and in position to attract the armature is an clectro-magnet incircuit with a source of current and with suitable circuit-closing andopening devices controlled or actuated by the master clock. Suchmake-and-break devices, which form no severable part of my presentinvention, may, as just stated, be of any suitable kind; but they shouldbe constructed and arranged so as to be actuated once every minute,thereby causing the escapement devices of all the subsidiary clocks inthe same circuit to be actuated simultaneously and hence causing eachclocktrain to advance one minute. The subsidiary clocks are thus kept inaccurate synchronism with the master clock wherever they may be located.

The preferred embodiment of the invention is illustrated in the annexeddrawing, in which Figure 1 is a front view of a clock mechanism, withthe upper portion of the front frame plate broken away to show thesynchronizing attachment. Fig. 2 is a side view of the same, the upperportions of the frame plates being in cross section.

The minute spindle of the clock is designated by 1, and is provided witha lanternpinion 2 engaging the power-driven gear 3, and a gear 2 in meshwith a lantern gear 2* on a countershaft- 2 The latter has also a gear 2in mesh with a lantern pinion L on the escapement shaft or arbor 5.Rigidly secured on the escapement shaft is the scape arm 6, which may beprovided with an eX- tension 7 on the opposite side of the shaft toserve as a counterbalance. Said shaft may also be provided with asuitable steadying vane 8 if desired.

The anchor or scape lever 9 is rigidly mounted on the shaft 10 above thescape arm, and extending upwardly from said shaft is an armature 11fastened thereto. Mounted on a suitable support 12 is an electro-magnet13, arranged with its poles in position to attract the armature 11 andso oscillate the anchor 9. In order to hold the armature normally awayfrom the magnet the former is provided with an arm 14: extendingrearwardly with respect to the magnet, so that the Weight of said armwill serve to hold the armature in the desired normal position, as shownin full lines in Fig. 1. This arm may be simply a piece of wire fixed tothe armature, and in order to have suflicient weight for the purposeintended it may be of some length, the portion which might otherwiseproject beyond the clock frame being coiled as shown. This arrangementalso serves as a convenient means for regulating the separation of thearmature from the magnet cores. For this purpose the coiled portion isarranged to rest on the cross rod 15 of the clock frame, and it will beseen that the normal distance between the magnet cores and the armaturecan be varied as desired merely by suitably expanding or contracting thecoiled portion of the gravity arm let.

It will be understood, of course, that the magnet 13 is in a circuitwhich is provided with suitable make-andbreak devices actuated atuniform intervals by a master clock, not shown. The present embodimentis designed for a normally open circuit, and hence the position of theparts which is shown in Fig. 1, with the armature retracted from themagnet, is the normal position. In this position the scape arm 6 restsagainst the holding pallet 16, the other or right hand pallet 17 beingraised.

From the foregoing description the operation of the device will bereadily understood. At each closing of the magnet circuit by the masterclock the armature 11 is drawn over toward the magnet, thereby liftingthe holding pallet and releasing the scape arm 6, which immediatelyflies around to the position shown in dotted lines in Fig. 1, where itstrikes the right hand pallet 17 which has been lowered by the actuationof the anchor. Immediately, however, after the closing of the circuitthe circuit is broken again, by the master clock, whereupon the armatureand the anchor return to their normal positions, releasing the scape armfrom the right hand pallet and permitting the said arm to continue itsmovement until it brings up against the holding pallet 16. It willtherefore be seen that at each make-and-break of the synchronizingcircuit the scape arm makes a complete revolution, permitting the clocktrain to advance to a corresponding extent, which of course should be inexact correspondence with the time-interval between each make-andbreakand the succeeding make-and-break. This time-interval may be one second,ten seconds, one minute, or any other interval de sired; but aspreviously stated, I prefer to have it one minute, since that is thesmallest division of time which time-recorders as ordinarily constructedtake account of. In such case the reduction from the escapement shaft atto the minute spindle 1 should of course be in the ratio of G0 to 1, sothat at each revolution of the escapement shaft the -minute spindle willbe advanced one-sixtieth of a revolution, or one minute.

It is to be understood that the construction herein specificallydescribed is merely the preferred embodiment of the invention, which maybe embodied in various forms without departure from its proper scope asdefined by the following claims.

lVhat I claim is:

The combination of an escapement arbor having a scape-arm, an anchorarranged to oscillate in the path of the scape-ari'n, an armatureconnected with the anchor, an electromagnet arranged to attract thearmature and thereby swing,the anchor in one direction, a weight-armassociated with the armature to retract the same when the magnet isdeenergized, and a stop in the path of the weight-arm to limit theretraction of the armature, said weight-arm comprising a strip ofpliable material having the portion engaging the said step arranged inexpansible and contractible convolutions whereby the extent ofretraction of the armature may be varied without substantial variationin the retracting force of said arm, as set forth.

BENJAMIN r. MERRITT. [1 s] lVitnesses S. H. CHAMBERLAIN, G. F. REID.

